Chen, who had previously confirmed to Olympics.com that he would seek to defend his world title, has picked up an injury, according to U.S. Figure Skating, which made the announcement in a press release on Wednesday (16 March).
"I am disappointed to have to withdraw from Worlds," Chen said. "I have been training for this competition since returning from Beijing.
"I have a nagging injury that I've been dealing with, and I don’t want to risk further injury by practicing and competing next week."
U.S. Figure Skating announced that Camden Pulkinen will replace the Olympic champion at the World Championships, which run from 23–27 March in Montpellier, France.
Pulkinen was one of three American skaters listed as alternates for the event, alongside Jason Brown and Jimmy Ma.
Between them, Chen and Hanyu have won the last four titles; no man in the field has previously won world gold.
It also means there will be first-time world champions in at least two of the four events – men's and women's – with first-time champions also likely in the pairs event.